Choice of fuel

Short competitive period

Before competitions that last for up to 1 hour, no particular dietary adjustment is necessary, since the body’s normal glycogen stores are sufficient. An unnecessarily high carbohydrate intake results in a weight increase as considerable quantities of fluid are bound in muscles and liver during glycogen storage (1 g of sugar binds 2–3 ml of water).3–4 hours before every competition a light meal should be eaten.

Long competitive period

Before competitions of 1–3 hours’ duration, some consideration should be given to dietary preparations.Sports such as walking, running, orienteering, cycling, skiing and canoeing, which depend upon physical fitness, are liable to use up the available glycogen during the course of the competition. Therefore in the days leading up to the competition, meals should include food rich in carbohydrates. As it takes about 48 hours for glycogen stores to be built up, no prolonged or hard training that would deplete the stores should take place in the 48 hours prior to the competition.

Prolonged competitive periods

In competitions that last for over 3 hours (for example, marathon races), the final result is to some extent dependent on the glycogen content of the body at the outset.